https://gitlab.synchro.net/main/sbbs/-/issues/1141#note_8976
Just a suggestion... I'd start by detecting the position, sending a multi byte character sequence, such as an emoji with skin tone.. then detect the cursor position. This should allow you to determine utf-8 support...
With that you can assume certain upstream terminal support... You can also query/test for rgb color support.
--- SBBSecho 3.37-Linux
* Origin: Vertrauen - [vert/cvs/bbs].synchro.net (1:103/705)